Meeting Abstract
Hydrodynamic stability and the ability to turn are two important components of swimming performance in aquatic animals. Stability reduces the energetic costs of swimming, which can constitute most of the daily energy budget of an aquatic animal. In addition, turning performance is critical for both prey capture and predator avoidance. These components of locomotor performance are most commonly measured in adult individuals; however, juveniles often experience stronger selection and higher mortality than adults, placing high demands on these aspects of their locomotor performance. To test how stability and turning performance change in a rigid-bodied, swimming species through ontogeny, we recorded high-speed video of pink-bellied sideneck turtles (Emydura subglobosa) as they swam through water following a prey stimulus. We compared the performance of juvenile turtles to adults, and used linear and geometric morphometrics to evaluate changes in limb and body shape as the species increased in size. Our results show that E. subglobosa are less stable as juveniles than as adults, especially with respect to heave and sideslip. Juveniles are also more circular in shape than adults, which may contribute to differences in turning performance as size increases. Thus, juvenile turtles do not perform equivalently to adults in these aspects of aquatic locomotion, despite their high vulnerability to pressures that place demands on such performance. Size-related differences in morphology and kinematics likely contribute to these performance differences.
